The invention relates to a circular buffer for a TDMA data transmission station and a TDMA data transmission station having a circular buffer.
In example of a TDMA (Time Division Multiple Access) data transmission system is the DECT (Digital Enhanced Cordless Telephone) system. In TDMA systems, data transmission in time division multiplex occurs during so-called time slots. The composition of data transmitted during a DECT time slot is described in detail below in conjunction with FIG. 3. Such devices are quite complex.
It is accordingly an object of the invention to provide a circular buffer for a TDMA data transmission station ana a corresponding data transmission station, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which enable data transmitted in bursts but occurring or to be processed continuously in a TDMA data transmission station to be temporarily stored with the least possible complexity.
With the foregoing and other objects in view there is provided, in accordance with the invention, a single circular buffer for a TDMA data transmission station, comprising temporary storage for both digital transmit data occurring during a number of time slots in the transmission station and to be transmitted during a subsequent transmit time slot, and digital receive data received by the transmission station during a receive time slot and to be processed by it in a number of subsequent time slots.
A singular circular buffer for temporarily storing both transmit and receive data has the advantage that the configuration of the transmission station is simplified and the total storage required for storing the receive and transmit data can even be reduced as compared with separate buffers.
In accordance with another feature of the invention, the number of transmit data to be transmitted during a transmit time slot is just as large as the number of receive data to be received by the transmission station during a receive time slot, and the storage capacity of the circular buffer is 1.5 times that number.
In accordance with a further feature of the invention, receive data temporarily stored in the circular buffer during a receive time slot are overwritten, in an order in which they have been temporarily stored, by transmit data to be transmitted in a subsequent transmit time slot.
In accordance with an added feature of the invention, the circular buffer is provided for a DECT data transmission station and the respective transmit and receive data are user data of B fields which are transmitted within one DECT time slot each. A B field contains 40 bytes user data. The circular buffer according to the invention therefore has a storage capacity of only 60 bytes instead of the 80 bytes required with two separate buffers. The reduction of the storage requirement of the common circular buffer is based on the finding that the respective transmit and receive data are transmitted at different times and thus all bits of a B field only need to be temporarily stored during one transmit time slot for the transmit data and only during one receive time slot for the receive data while the other type of data in each case has a maximum storage requirement of 20 bytes at the same time.
With the objects of the invention in view there is also provided a TDMA data transmission station, comprising the circular buffer, in which a change of the receive time slot is immediately followed by a change of the transmit time slot, unless the transmit time slot has already changed directly before the change of the receive time slot.
This measure ensures that even with the minimum storage capacity of the circular buffer of 1.5 times the number of data to be respectively transmitted or received during a time slot, no data are lost during a time slot change (hand-over).
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a circular buffer for a TDMA data transmission station and a corresponding data transmission station, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.